Heretofore, the best abrasive (other than cubic boron nitride) for use in vitrified grinding wheels for grinding tool steels, e.g. toolroom grinding, have been very high purity alumina grits preferably produced by fusion of alumina in a sulfide matrix, and are essentially mono-crystalline particles.
Recently alumina-spinel abrasives produced by the process of U.S. Pat. No. 4,314,827 have appeared on the market in coated abrasive products such as flexible cloth-bonded belts and fiber discs. Such abrasives, although they can be used in making conventional vitrified bonded grinding wheels, perform no better than the best alumina abrasive in dry grinding and are markedly less effective in wet grinding than the premium fused alumina abrasive.
It is an object of this invention to produce a vitrified grinding wheel containing an aluminous abrasive, made by sintering of an alumina gel, which is superior to the conventional fused alumina in vitrified grinding wheels.